JP2000248055A - Biodegradable aliphatic polyester copolymer and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide a biodegradable aliphatic polyester copolymer excellent in biodegradability, crushability, powder moldability, and the like, and a method for producing the same. SOLUTION: The present aliphatic polyester copolymer comprises:
(A) aliphatic diols (ethylene glycol, 1,3-
(B) aliphatic dicarboxylic acids (succinic acid, glutaric acid, adipic acid, sebacic acid, etc.), at least one of the acid anhydrides and diester compounds thereof, and (c) lactone (β-pro Piolactone,
γ-butyrolactone, ε-caprolactone, etc.) and / or a hydroxycarboxylic acid (glycolic acid, lactic acid, etc.), and are synthesized by polycondensation. 1 to 15 parts by weight, and the weight-average molecular weight of the biodegradable aliphatic polyester co-polymer is from 1500 to 20,000, and the ratio of weight-average molecular weight / number-average molecular weight is from 1.5 to 8.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable aliphatic polyester copolymer and a method for producing the same, and more particularly, to a biodegradable aliphatic polyester excellent in crushability and powder moldability as well as biodegradability. The present invention relates to a polyester copolymer and a method for producing the same.

[0002]

2. Description of the Related Art So far, biodegradable polymers have been studied as natural polymers such as starch and cellulose, microbial polymers such as cellulose and polysaccharides, and chemicals such as aliphatic polyesters. There are synthetic polymers. Among them, those which can be expected to have relatively low cost are natural product polymers and chemically synthesized polymers, and those which can relatively easily improve the performance by molecular design are chemically synthesized polymers.

[0003] In modern agriculture, spraying of pesticides is indispensable in order to increase the production of agricultural products while saving labor. Organic chlorine-based pesticides have long-term effects after spraying, but have the harmful effect of polluting the environment by remaining for a long time. On the other hand, organophosphorus pesticides are easily decomposed, so the duration is short, and if the amount of application is increased to maintain the effect, organisms other than pests will be killed. Become.
In addition, drugs that are administered for the treatment of diseases are also distributed quickly throughout the body, usually after being absorbed, and then metabolized and excreted outside the body. Will drop. If the dose is increased to maintain the therapeutic effect, there is a risk of the occurrence of side effects due to overdose.
It is annoying for the patient to take. Therefore, in order to maintain the effects of such pesticides and drugs over a long period of time, and to reduce the number of uses and the amount of use,
The sustained release is being studied, and among them, the development of a sustained release base material that allows the sustained release is being promoted.

[0004] As one of uses of the biodegradable polymer, when it is used as a sustained-release base material as described above, a granule as a typical shape has excellent biodegradability and excellent fine powder moldability. Is required. Generally, as the molecular weight of the aliphatic polyester copolymer decreases, the biodegradability tends to improve. Actually, when the weight average molecular weight is less than several thousand, the biodegradability is improved. However, when the molecular weight is reduced, the surface of the copolymer becomes viscous, and it tends to be difficult to pulverize the powder. This is because there are many liquid dicarboxylic acids or diols as raw materials for the aliphatic polyester copolymer, and if the copolymerization has not progressed sufficiently, these raw materials remain as unreacted materials and remain viscous. It is thought that it becomes to have. Further, in order to impart powder moldability such as hardness and brittleness to the aliphatic polyester copolymer, it is necessary to increase the molecular weight to some extent, but in this case, there is a problem that biodegradability is sacrificed. Conventionally, this problem has been solved by mixing several types of polymer compounds, but it is troublesome and not a good measure in terms of production. Therefore, at present, there is no aliphatic polyester-based biodegradable polymer that can be finely powdered and has good moldability, and a compound that can be used as a sustained-release base material has not been obtained. It is a fact.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a biodegradable aliphatic polyester copolymer having excellent biodegradability, crushability, powder moldability, and the like. It is an object of the present invention to provide a manufacturing method thereof.

[0006]

Means for Solving the Problems The present inventors have heretofore used polyethylene succinate (PESU) and polybutylene succinate (P) as biodegradable polymers in a chemically synthesized system.
(BSU) and the like containing a specific amount of a hydroxycarboxylic acid component have been studied (Japanese Patent Application No. 9-338).
No. 065). The present inventors have solved the problem of the above aliphatic polyester copolymer, and have excellent biodegradability, as well as an aliphatic polyester copolymer having crushability and powder moldability. As a result of the study, the aliphatic diol and aliphatic dicarboxylic acid were used as a copolymer containing a specific amount of a lactone or a hydroxycarboxylic acid component, and the weight average molecular weight was adjusted to 1500 to 20,000 to satisfy the powder moldability. Further, the ratio of the weight average molecular weight Mw of the polymer compound to the number average molecular weight Mn (Mw / M
n) is converse to the prior art, which is considered to be better when it is closer to 1.0 (closer to monodispersion). By expanding this to a predetermined range, a polymer compound having biodegradability can be obtained. The present invention has been completed by finding that it is possible.

That is, the biodegradable aliphatic polyester copolymer of the first invention comprises (a) an aliphatic diol and (b) at least one of aliphatic dicarboxylic acids, acid anhydrides and diester compounds thereof. And (c) polycondensation with lactone and / or hydroxycarboxylic acid. The content of the component (c) is determined by the total polyester copolymer 100
1 to 15 parts by weight with respect to parts by weight, and the weight-average molecular weight Mw of the biodegradable aliphatic polyester copolymer is 15
100 to 20,000, and the ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 1.5 to 8.0.

The “(a) aliphatic diol” includes:
What is necessary is just to provide two hydroxyl groups, and the carbon chain in the molecule may be cyclic or linear, or may have a branch. For example, as shown in the second invention, an aliphatic diol represented by the above general formula (1) having a hydroxyl group at both ends and having a linear carbon chain can be used. In the case of the aliphatic diol represented by the general formula (1), the number of carbon atoms (l) between the hydroxyl groups at both ends is preferably 2 to 4. If the carbon number is larger than this, the polyester is biodegraded into a dicarboxylic acid and a diol, and the resulting diol is not further biodegraded, and tends to accumulate in the environment. Such aliphatic diols include, for example, ethylene glycol, l, 3-propanediol, 1,4-butane-1-
Diols and the like can be mentioned. Among them, ethylene glycol is particularly preferable because it is inexpensive and economical.

The above-mentioned "(b) at least one of aliphatic dicarboxylic acids, acid anhydrides and diester compounds thereof"
May be one having two carboxyl groups or an acid anhydride or a diester compound that is a derivative thereof. The carbon chain in the molecule may be cyclic or linear, and may be branched. May be provided.
For example, as shown in the second invention, the above-mentioned general formula (2) having a carboxyl group at both ends and having a linear carbon chain
Or an acid anhydride or a diester compound thereof. In the case of the aliphatic carboxylic acid represented by the general formula (2), the number of carbon atoms (m) between the carboxylic acid groups at both ends is preferably 2 to 8 in consideration of the biodegradability of the polyester. Examples of the aliphatic dicarboxylic acid represented by the general formula (2) and the acid anhydride and the diester compound thereof include succinic acid, succinic anhydride, dimethyl succinate, glutaric acid, adipic acid, suberic acid, Azelaic acid, sebacic acid and the like can be mentioned. Among them, as shown in the third invention, succinic acid or succinic anhydride has high reactivity and is particularly preferable in terms of biodegradability. In addition, such aliphatic dicarboxylic acids, acid anhydrides or diester compounds thereof may be added alone or in combination of two or more.

In the component (c) of the first invention, the "lactone" may be any one that forms a lactone ring as represented by the general formula (3). It may have a branch, such as one having a hydrocarbon at the carbon to be formed. In the case of the lactone represented by the general formula (3), the number of carbon atoms (n) constituting the lactone ring is preferably 2 to 5 in consideration of the biodegradability of the polyester. Examples of such a lactone generally include those having no branch at the carbon constituting the lactone ring as shown in the second invention. For example, as shown in the fourth invention, β-propion Lactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone and the like. Among them, the use of ε-caprolactone is particularly preferable because the biodegradability of the product is improved.

In the component (c) of the first invention, the "hydroxycarboxylic acid" may be any one having a hydroxyl group and a carboxylic acid group. For example, as shown in the second invention, The compound represented by (4) is mentioned. Examples of the compound represented by the general formula (4) include glycolic acid in which X is a hydrogen atom and lactic acid in which X is a methyl group, as described in the fifth invention.
Among them, lactic acid is particularly preferred because the biodegradability of the product is improved. Lactic acid may be any of L-lactic acid, D-lactic acid, and DL-lactic acid, and is particularly preferable because L-lactic acid is easily available.

In the biodegradable aliphatic polyester copolymer of the first invention, (c) lactone and / or
Alternatively, the content of the hydroxycarboxylic acid is 1 to 15 parts by weight, preferably 3 to 10 parts by weight, more preferably 5 to 8 parts by weight based on 100 parts by weight of the entire polyester copolymer. If the content is less than 1 part by weight, the biodegradability is not improved because no improvement is observed. If the content exceeds 15 parts by weight, the copolymer becomes viscous and the powder moldability, which is the main object of the present invention, is reduced. Is not preferred.

The amount of the "(a) aliphatic diol" used is usually from 1.0 to 1.2, preferably from 1.05 to 1 in molar ratio to the amount of the component (b). .10
It is. If the amount used is less than 1.0, the diol component becomes insufficient, and both ends of the molecular chain become carboxylic acid or carboxylic acid dimethyl ester, and polycondensation ends, and the molecular weight does not increase. If it exceeds, the amount of the diol component distilled off in the diol removal reaction increases, and the reaction time is unnecessarily long, which is not preferable.

The biodegradable aliphatic polyester copolymer of the first invention contains a low molecular weight component and has a wide molecular weight distribution. The low molecular weight component has an effect of improving the biodegradability, and when this component is removed by reprecipitation or the like, the biodegradability decreases. The ratio (Mw / Mn) between the weight average molecular weight Mw and the number average molecular weight Mn as an index of the distribution is 1.5 to 8.0, preferably 1.5 to 5.0, and more preferably 1.5 to 3 .
0. If the ratio is less than 1.5, the low molecular weight component is insufficient, and the biodegradability of the copolymer is not improved. If the ratio is more than 8.0, the physical properties (melting point, powder moldability, etc.) of the copolymer are not obtained. Is difficult to control. In this case, the number average molecular weight Mn is 500 to 1300.
0, preferably 1,000 to 10,000, while the weight average molecular weight Mw is 1500 to 20,000, preferably 2,500 to 18,000. The weight average molecular weight can be arbitrarily changed by adjusting the reaction time and the degree of vacuum, but if it is less than 1500, the mechanical strength becomes insufficient, and if it exceeds 20,000, the desired biodegradability is not obtained, which is not preferable. .

The weight loss rate of the biodegradable aliphatic polyester copolymer of the first invention by enzymatic hydrolysis, ie, the biodegradability, is 10% by weight or more, for example, 10 to 30% by the following test method. %, Preferably 15% by weight or more, for example, 15 to 30% by weight. [Test Method] The product was formed into a square test piece having a vertical axis of 10 mm, a horizontal axis of 10 mm, and a thickness of 1 mm, and containing p-lipase (trade name "Lipase PS" manufactured by Amano Pharmaceutical Co., Ltd.)
H5.9 in 5 ml of phosphate buffer solution (“Lip
(the concentration of “ase PS” is 0.02 g / ml), left at 50 ° C. for 7 hours, dried, and the amount of weight loss is measured. Further, the melting point of the biodegradable aliphatic polyester copolymer of the present invention is 60 to 100 ° C, preferably 80 to 90 ° C. The biodegradable aliphatic polyester copolymer of the present invention,
Even when kneading with thermally unstable organic or inorganic compounds,
It does not cause much damage to them.

The method for producing the biodegradable aliphatic polyester copolymer of the first to fifth aspects of the present invention is not particularly limited, but the reaction conditions are usually the same as those described above under normal pressure and subsequently under reduced pressure. A production method in which the components a), (b) and (c) are subjected to polycondensation is preferred. The method for producing a biodegradable aliphatic polyester copolymer of the sixth invention comprises: (a) an aliphatic diol; and (b) at least one of an aliphatic dicarboxylic acid, an acid anhydride thereof, and a diester compound thereof.
(C) lactone and / or hydroxycarboxylic acid,
The polycondensation is carried out at 150 to 200 ° C. under normal pressure while blowing an inert gas into the reaction solution. At this time, the proportion of the component (c) is determined by the component (a), the component (b) and the component (c). Is 1 to 15 parts by weight when the total of is 100 parts by weight, and then 150 to 200 ° C. at 0.1 to 10 mmHg.
And the weight average molecular weight Mw is from 1500 to 20
It is characterized in that a biodegradable aliphatic polyester copolymer having a weight average molecular weight Mw and a number average molecular weight Mn (Mw / Mn) of 1.5 to 8.0 is produced.

In the present invention, the reaction is generally carried out at normal pressure and subsequently at reduced pressure. The reaction is carried out at a temperature of 150 to 200 ° C. while blowing an inert gas into the reaction solution for 2 to 5 hours until the distillation of water or methanol stops. If the temperature is lower than this temperature, the reaction rate becomes slow and is not practical. If the temperature is higher than this temperature, the possibility of thermal decomposition or coloring of the polymer increases, which is not preferable. The process of shifting from the normal pressure reaction to the reduced pressure reaction is performed by first blowing 180 to 200
The pressure is gradually reduced to 10 mmHg at a temperature of about 2 to 8 hours, preferably about 3 to 5 hours. 180-200
If the reaction time is less than 2 hours at ° C, the pressure is reduced in a state where the progress of the polycondensation is not sufficient, and the component having a low degree of polymerization is distilled off, so that the yield is reduced. 8 reaction times
Even if the time exceeds the time, the yield does not increase so much. It is uneconomical to spend more time. Therefore, it is sufficient to gradually reduce the pressure in about 3 to 5 hours. The vacuum polycondensation reaction is
The reaction solution is blown with an inert gas at 180 to 200 ° C at 1 to 10 mmHg for 5 to 15 hours, preferably 8 to 1 hour.
Perform for 0 hours. At this point, the molecular weight reaches up to about 10,000. In order to further increase the molecular weight, the degree of vacuum should be 0.1
Continue the reaction at ~ 1 mmHg. Reaction time 10-18
In time the molecular weight reaches 15,000 to 20,000. In the above production method, when the total of the components (a), (b) and (c) is 100 parts by weight, the proportion of the component (c) is 1 to 15 parts by weight, so that the weight average molecular weight is reduced. 15,000 to 20,000, number average molecular weight of 500 to 13
It is possible to produce a biodegradable aliphatic polyester copolymer in the range of 000.

In the manufacturing method according to the sixth invention, Ti, G
Metallic inclusions such as e and Sb, preferably alkoxides thereof, and organometallic compounds such as acetylacetonate can be used as a catalyst. Among them, organometallic compounds of Ti, such as tetraisopropyl titanate and tetrabutyl titanate, are particularly preferred because they have no toxicity and high activity. The amount of the catalyst is usually 0.05 to 1 part by weight, preferably 0.1 to 0.5 part by weight, based on 100 parts by weight of the total amount of the monomer raw materials. If the amount exceeds 1 part by weight, coloring may be caused.

In the above reaction, an inert gas is blown for the purpose of preventing oxidative polymerization of the polymer and providing an air flow for efficiently distilling volatile components.
As the inert gas, nitrogen, argon, helium, or the like can be used. The flow rate of the inert gas is 10 to 50
ml / min, preferably 10 to 40 ml / min. When the flow rate is less than 10 ml / min, there is no blowing effect, the molecular weight is hardly increased, and the flow rate is 50 ml / m.
This is because the degree of vacuum does not rise sufficiently even if the temperature exceeds in, and the reaction time is reduced.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the biodegradable aliphatic polyester copolymer of the present invention will be specifically described with reference to Examples and Comparative Examples. (1) Production of Biodegradable Aliphatic Polyester Copolymer Examples 1 to 5 and Comparative Examples 1 to 4 were prepared by the following method.
The above biodegradable aliphatic polyester copolymers were produced.

EXAMPLE 1 Succinic anhydride 250 was placed in a four-necked reaction vessel equipped with a stirrer, a vacuum pump (including a cooler), a thermometer, and a gas inlet tube.
0 g, ethylene glycol 1700 g, L-lactic acid 450
g, tetrabutyl titanate 2.5 g, and nitrogen gas at a flow rate of 40 ml / min.
After the esterification reaction was performed for 3.5 hours by heating to 40 ° C., while blowing nitrogen gas at a flow rate of 40 ml / min, 1
While maintaining 90 ° C, while gradually reducing the pressure with a vacuum pump,
The pressure was finally reduced to 1 mmHg over 3 hours. Next, the flow rate of the nitrogen gas was set to 15 ml / min and 1 mmH
g polycondensation reaction at 190 ° C. for 0.5 hour under reduced pressure,
The biodegradable aliphatic polyester copolymer of Example 1 was obtained.

Example 2 Under the same reaction conditions as in Example 1 and under a reduced pressure of 1 mmHg,
The polycondensation at 90 ° C. was performed for 9.5 hours to obtain the biodegradable aliphatic polyester copolymer of Example 2.

Example 3 Under the same reaction conditions as in Example 1, under a reduced pressure of 1 mmHg,
After performing 9.5 hours of polycondensation at 90 ° C., 0.6 mmHg
At 190 ° C. for 6 hours to obtain a biodegradable aliphatic polyester copolymer of Example 3.

Example 4 Under the same reaction conditions as in Example 1, polycondensation at 1 mmHg and 190 ° C. was performed for 9.5 hours, and then 0.6 mmHg and 190 ° C.
The reaction was performed at 12 ° C. for 12 hours to obtain a biodegradable aliphatic polyester copolymer of Example 4.

Example 5 The compounding amount of L-lactic acid, one of the raw materials of Example 1, was 700
1 mmH under the same reaction conditions as in Example 1 except that
g, after 9.5 hours of polycondensation at 190 ° C.
The reaction was carried out at mHg and 190 ° C. for 12 hours to obtain a biodegradable aliphatic polyester copolymer of Example 5.

Comparative Example 1 The reaction was carried out under the same conditions as in Example 1 except that L-lactic acid was omitted, to obtain a biodegradable aliphatic polyester copolymer of Comparative Example 1.

Comparative Example 2 5 g of the biodegradable aliphatic polyester copolymer of Example 1 was dissolved in 50 g of chloroform.
The mixture was reprecipitated by adding ml and filtered. Next, this precipitate was dissolved in 50 g of chloroform, and methanol 200m
1 and re-precipitation, and the operation of filtering is performed three times in total.
The biodegradable aliphatic polyester copolymer of Comparative Example 2 was obtained as the precipitate.

COMPARATIVE EXAMPLE 3 Under the same reaction conditions as in Example 1, polycondensation at 1 mmHg and 190 ° C. was performed for 9.5 hours.
The reaction was performed at 20 ° C. for 20 hours to obtain a biodegradable aliphatic polyester copolymer of Comparative Example 3.

Comparative Example 4 The compounding amount of L-lactic acid, one of the raw materials of Example 1, was 130
Except for 0 g, 1 mmH under the same reaction conditions as in Example 1.
g, after 9.5 hours of polycondensation at 190 ° C.
The reaction was carried out at mHg and 190 ° C. for 12 hours to obtain a biodegradable aliphatic polyester copolymer of Comparative Example 4.

(2) Performance test Examples 1 to 5 and Comparative example 1 obtained by the above production method
The weight average molecular weight (M) of each of the biodegradable aliphatic polyester copolymers of Nos. 1 to 4 was determined by the method described below.
w), number average molecular weight (Mn), hydroxycarboxylic acid content (HA), melting point (Tm), enzymatic hydrolysis weight loss rate and powder moldability were measured. The results are shown in Table 1 below. [1] Method of measuring average molecular weight A GPC measuring device manufactured by Tosoh Corporation was used, and the column was T
SK-gel G-2500, G-3000, G-40
00 was used in conjunction. Chloroform was used as the eluate, the measurement was performed at 40 ° C., and conversion was performed using polystyrene as the standard substance. [2] Hydroxycarboxylic acid content ¹ H-NMR was measured using a 2000 MHz-NMR measuring device manufactured by Bruker Japan, and the HA content was calculated from the signal intensity ratio. The measurement was performed using a heavy chloroform solution. Tetramethylsilane was used as an internal standard. [3] Melting point (Tm) The melting point (Tm) was measured using a DSC measuring device manufactured by Seiko Electronics Industry Co., Ltd. In the case of the biodegradable aliphatic polyester copolymer of Comparative Example 4, the temperature range was wide and the melting point could not be measured accurately. Therefore, the term of the melting point in Table 1 is indicated by "-". [4] Weight loss rate due to hydrolysis Each of the biodegradable aliphatic polyester copolymers of Examples 1 to 5 and Comparative Examples 1 to 4 was formed into a square test piece having a vertical axis of 10 mm, a horizontal axis of 10 mm, and a thickness of 1 mm. And lipase (manufactured by Amano Pharmaceutical Co., Ltd., trade name "Lipase PS") containing p
H5.9 in 5 ml of phosphate buffer solution (“Lip
The concentration of “ase PS” was 0.02 g / ml), the mixture was allowed to stand at 50 ° C. for 7 hours, dried, and the weight loss rate was measured.
This molding method is melt molding. [5] Powder moldability Each of the biodegradable aliphatic polyester copolymers of Examples 1 to 5 and Comparative Examples 1 to 4 is formed into a shape of about 5 mm square, and the state when it is refined while hitting with a hammer is shown. The powder moldability was evaluated by visual observation. In Table 1,
"Good" means that the material could be crushed to about 0.1 mm square, and "Bad" means that the material adhered to the hammer or the fine particles adhered again and returned to large particles. Is shown.

[0031]

[Table 1]

(3) Effects of Examples From the results shown in Table 1, each of the biodegradable aliphatic polyester copolymers obtained in Examples 1 to 5 is excellent in biodegradability and powder moldability. You can see that. In particular, Examples 1 and 2 having a small weight average molecular weight are excellent in powder moldability, and have a biodegradability with a weight reduction rate of 29% and 2%.
It can be seen that 1% is superior to the other examples. On the other hand, in the copolymer, each biodegradable aliphatic polyester copolymer of Comparative Example 1 not containing L-lactic acid as the component (c) and Comparative Example 2 having Mw / Mn lower than the lower limit of 1.24. It can be seen that the product had a lower biodegradability in all cases as compared with Examples 1 to 5 at a weight reduction rate of about 3 to 6%. In particular, Comparative Example 1, which does not contain L-lactic acid as the component (c) in the copolymer, has a weight loss rate of 3% and is extremely poor in biodegradability. It can be seen that it must be a biodegradable aliphatic polyester copolymer containing L-lactic acid as a component. Further, Mw / Mn is 1.2
Comparative Example 2, which is lower than the lower limit of 4, has a biodegradability of 29 as compared with Example 1 in which the weight average molecular weight is almost the same.
% To 6%. In Comparative Example 2, as a result of removing low molecular weight components from the biodegradable aliphatic polyester copolymer of Example 1 by chloroform and methanol extraction, the number average molecular weight increased and the value of Mw / Mn decreased. Things. Therefore, it can be seen that in order to improve the biodegradability, it is necessary to set Mw / Mn in the range of 1.5 to 8.0 and to include a low molecular weight component.

From the results in Table 1, the powder moldability of each of the biodegradable aliphatic polyester copolymers of Examples 1 to 5 is
While all were good, the weight average molecular weight Mw was 2
It can be seen that in Comparative Example 3 in which the upper limit value was 1000 and 1000, and in Comparative Example 4 in which the HA content was higher than the upper limit value of 20%, the powder moldability was poor. In Comparative Example 3, although Mw / Mn was almost the same as Examples 4 and 5, the weight loss rate was 11%, indicating that the biodegradability was slightly inferior. In addition, since the powder moldability is also poor, in order to improve the biodegradability and the powder moldability, not only the Mw / Mn should be within a predetermined range but also the biodegradable aliphatic polyester copolymer. This indicates that the weight average molecular weight Mw also needs to be within a predetermined range. In Comparative Example 4, in which the amount of L-lactic acid was large, the weight reduction rate was 14%, which was higher than Examples 4 and 5, but the powder moldability was poor. That is, in this example, it is shown that the L-lactic acid component is essential for improving the biodegradability, but there is a limit to the content of the L-lactic acid component for achieving compatibility with the powder moldability.

It should be noted that the present invention is not limited to the specific embodiments described above, but can be variously modified within the scope of the present invention according to the purpose and application.

[0035]

The biodegradable aliphatic polyester copolymer of the present invention has good biodegradability and excellent crushability and powder moldability, so that it can be applied to various uses. For example, it can be used as a base material for controlling the release of a drug to give sustainability, such as a sustained-release medicine, a sustained-release pesticide base material, and the like.

Claims (6)

[Claims] 1. Polycondensation of (a) an aliphatic diol, (b) at least one of an aliphatic dicarboxylic acid, an acid anhydride thereof and a diester compound thereof, and (c) a lactone and / or a hydroxycarboxylic acid. The content of the component (c) is 1 to 15 parts by weight based on 100 parts by weight of the entire polyester copolymer, and the weight-average molecular weight Mw of the biodegradable aliphatic polyester copolymer is: 1500-2
A biodegradable aliphatic polyester copolymer having a weight average molecular weight Mw and a number average molecular weight Mn (Mw / Mn) of 1.5 to 8.0. 2. The above (a) aliphatic diol is a structural formula represented by the following general formula (1) (wherein, l represents an integer of 2 to 4), and the above (b) aliphatic dicarboxylic acid Is a structural formula represented by the following general formula (2) (where m represents an integer of 2 to 8), and among the components (c), the lactone has a structure represented by the following general formula (3) Where n is 2 to
Represents an integer of 5. The biodegradable aliphatic polyester copolymer according to claim 1, wherein the hydroxycarboxylic acid is a structural formula represented by the following general formula (4), wherein X represents a hydrogen atom or a methyl group. Embedded image Embedded image Embedded image Embedded image 3. The biodegradable aliphatic polyester copolyester according to claim 1, wherein the aliphatic dicarboxylic acid of the component (b) is succinic acid, and the acid anhydride is succinic anhydride. 4. The lactone of component (c) is one or more selected from β-propiolactone, γ-butyrolactone, δ-valerolactone and ε-caprolactone. The biodegradable aliphatic polyester copolymer described in Crab. 5. The biodegradable aliphatic polyester copolymer according to claim 1, wherein the hydroxycarboxylic acid of the component (c) is glycolic acid and / or L-lactic acid. 6. A method comprising: (a) an aliphatic diol, (b) at least one of an aliphatic dicarboxylic acid, an acid anhydride thereof and a diester compound thereof, and (c) a lactone and / or a hydroxycarboxylic acid under normal pressure. The polycondensation is carried out while blowing an inert gas into the reaction solution at 150 to 200 ° C., wherein the proportion of the component (c) is the same as that of the component (a) and the component (b).
When the total of the component and the component (c) is 100 parts by weight, the amount is 1 to 15 parts by weight, and thereafter, 0.1 to 10 mmHg.
At 150 to 200 ° C. to obtain a weight average molecular weight M
w is 1500 to 20,000, and the ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 1.5 to
8. A method for producing a biodegradable aliphatic polyester copolymer, which comprises producing a biodegradable aliphatic polyester copolymer having a molecular weight of 8.0.